1. Field of Invention
The invention relates generally to a method for boring through a workpiece. More specifically, the present invention relates to a method of using a gun drill to form a bore in a workpiece, and steering the drill while boring.
2. Description of Prior Art
Elongated bores formed in manufactured articles are typically formed with an elongate drill. One such type of drill is a gun drill that is cylindrical and is fluted along a portion of its length. The cutting edge of a gun drill is generally at a forward end of the flute. Some gun drills have a cutting edge with a V-shaped edge. However, due to many variables, conventional gun drilling has centerline deviations that are not predictable in direction. Due to their shapes, gun drills often have an eccentric second moment of inertia. Moreover, gun drills usually flex, bend, and twist easily, due at least in part to their high length/diameter rations (l/d>100). During the machining process in metal the cutting speed and the feed rate lead to torsion oscillations and twisting. Consequences of deviations in bore centerline are exacerbated when multiple bores are being formed in a particular workpiece.